1. Field of Invention
This invention relates to the field of high current LED driver.
2. Background of the Invention
High brightness and high current light emitting diodes (LED) are increasingly being used as high intensity light sources. High intensity LEDs provide many benefits over other high intensity light sources, such as longer life, wider color range, less hazardous operating voltages, and higher efficiency. In some rear projection TVs and front projection systems the light from an LED is required to be switched very rapidly as required by the Digital Micromirror Device (DMD).
The digital micromirror device (DMD) imager is a digital light valve that either reflects or deflects a light source. Color images are formed by sequentially shining the DMD with a Red, Green and Blue light source and by temporal modulation of the intensity of the light reflected from each DMD pixel. Because of this fast modulation the DMD imager requires a red, blue, and green LED to be switched on and off very fast which necessitates the LED current to be switched ON and OFF very fast. The current switching required has been difficult with conventional means. In the past the switching of current to an LED was accomplished by charging and discharging the inductor in a switching regulator. In this case switching regulators with high efficiency are highly desirable to prevent excessive power loss as a result of switching several amperes of current. This suffers from many shortcomings, most importantly the difficulty in switching the current as quickly as needed.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.